IPTV (Internet Protocol Television) is a system where a digital television service is delivered by using Internet Protocol over a network infrastructure, which may include delivery by a broadband connection. A general definition of IPTV is television content that, instead of being delivered through traditional broadcast and cable formats, is received by the viewer through the technologies used for computer networks.
For residential users, IPTV is often provided in conjunction with Video on Demand and may be bundled with Internet services such as Web access and Voice over IP (“VoIP”). The commercial bundling of IPTV, VoIP and Internet access is referred to as “Triple Play” service (adding mobility is called “Quadruple Play”). IPTV is typically supplied by a service provider using a closed network infrastructure. This closed network approach is in competition with the delivery of TV content over the public Internet, called Internet Television. In businesses, IPTV may be used to deliver television content over corporate LANs.
In 1994, ABC's World News Now was the first television show to be broadcast over the Internet, using the CU-SeeMe videoconferencing software. The term IPTV first appeared in 1995 with the founding of Precept Software by Judith Estrin and Bill Carrico. Precept designed and built an internet video product named “IP/TV”. IP/TV was an MBONE compatible Windows and Unix based application that moved single and multi-source audio/video traffic, ranging from low to DVD quality, using both unicast and IP multicast RTP/RTCP. The software was written primarily by Steve Casner, Karl Auerbach, and Cha Chee Kuan. Precept was acquired by Cisco Systems in 1998. Cisco retains the “IP/TV” trademark.
Internet radio company AudioNet started the first continuous live webcasts with content from WFAA-TV in January, 1998 and KCTU-LP on Jan. 10, 1998. Kingston Communications, a regional telecommunications operator in UK, launched KIT (Kingston Interactive Television), an IPTV over DSL broadband interactive TV service in September 1999 after conducting various TV and VoD trials. The operator added additional VoD service in October 2001 with Yes TV, a provider of VoD content. Kingston was one of the first companies in the world to introduce IPTV and IP VOD over ADSL.
In the past, this technology has been restricted by low broadband penetration. In the coming years, however, residential IPTV is expected to grow at a brisk pace as broadband was made available to more than 200 million households worldwide in the year 2005, projected to grow to 400 million by the year 2010. Many of the world's major telecommunications providers are exploring IPTV as a new revenue opportunity from their existing markets and as a defensive measure against encroachment from more conventional Cable Television services. In the mean time, there are thousands of IPTV installations within schools, corporations, and other institutions that do not require the use of wide area connectivity.
It is important to note that historically there have been many different definitions of “IPTV” including elementary streams over IP networks, transport streams over IP networks and a number of proprietary systems. Although (in Mid 2007) it is premature to say that there is a full consensus of exactly what IPTV should mean, there is no doubt that the most widely used definition today is for single or multiple program transport streams which are sourced by the same network operator that owns or directly controls the “Final Mile” to the consumer's premises. This control over delivery enables a guaranteed quality of service, and also allows the service provider to offer an enhanced user experience such as better program guide, interactive services etc.
In 2006, AT&T launched its U-Verse IPTV service. Comprised of a national head end and regional video serving offices, AT&T offered over 300 channels in 11 cities with more to be added in 2007 and beyond. While using IP protocols, AT&T has built a private IP network exclusively for video transport. IPTV uses a two-way digital broadcast signal sent through a switched telephone or cable network by way of a broadband connection and a set-top box programmed with software (much like a cable or DSS box) that can handle viewer requests to access to many available media sources.
FIG. 1 shows an exemplary IPTV distribution network architecture, starting from a “Headend” on the left side of the figure, and culminating with a viewer set-top boxes (“STB”) and other media presentation appliances on the right side of the figure. Currently, California based UTStarcom, Inc. and Tennessee based Worley Consulting are two companies offering end-to-end networking infrastructure for IPTV-based services.
IPTV covers both live TV (multicasting) as well as stored video (Video on Demand VOD). The playback of IPTV requires either a personal computer or a set-top box connected to a TV. Video content is typically compressed using either a MPEG-2 or a MPEG-4 codec and then sent in an MPEG transport stream delivered via IP Multicast in case of live TV or via IP Unicast in case of Video on Demand. IP Multicast is a method in which information can be sent to multiple computers at the same time. The newly released (MPEG-4) H.264 codec is increasingly used to replace the older MPEG-2 codec.
In standards-based IPTV systems, the primary underlying protocols used for Live TV is using IGMP version 2 for connecting to a multicast stream (TV channel) and for changing from one multicast stream to another multicast stream (TV channel change). Video on Demand (“VOD”) generally uses the Real Time Streaming Protocol (RTSP). Currently, the only alternatives to IPTV are traditional TV distribution technologies such as terrestrial, satellite and cable. However, cable can be upgraded to two-way capability and can thus also carry IPTV.
Network Personal Video Recording is a consumer service where real-time broadcast television is captured in the network on a server allowing the end user to access the recorded programs on the schedule of their choice, rather than being tied to the broadcast schedule. The NPVR system provides time-shifted viewing of broadcast programs, allowing subscribers to record and watch programs at their convenience, without the requirement of a truly personal PVR device. It could be compared as a “PVR that is built into the network”—however that would be slightly misleading unless the word “Personal” is, of course, changed to “Public” for this context.
The IP-based video distribution platform offers significant advantages over traditional distribution platform, including the ability to integrate television with other IP-based services like high speed Internet access and VoIP. A switched IP network also allows for the delivery of significantly more content and functionality. In a typical TV or satellite network, using broadcast video technology, all the content constantly flows downstream to each customer, and the customer switches the content at the set-top box. The customer can select from as many choices as the telecomms, cable or satellite company can stuff into the “pipe” flowing into the home. A switched IP network works differently. Content remains in the network, and only the content the customer selects is sent into the customer's home. That frees up bandwidth, and the customer's choice is less restricted by the size of the “pipe” into the home.
Because IPTV requires real-time data transmission and uses the Internet Protocol, it is sensitive to packet loss and delays if the IPTV connection is not fast enough, or picture break-up or loss if the streamed data is unreliable. This latter problem has proved particularly troublesome when attempting to stream IPTV across wireless links. Improvements in wireless technology are now starting to provide equipment to solve the problem.
The venerable set-top box, on its way out in the cable world, made resurgence in IPTV systems. The box connects to the home DSL line and is responsible for reassembling the packets into a coherent video stream and then decoding the contents. Computers could do the same job, but most people still don't have an always-on PC sitting beside the TV, so the box has made a comeback.
As shown in FIG. 1, most video enters the system at the telco's national headend, where network feeds are pulled from satellites and encoded if necessary (often in MPEG-2, though H.264 and Windows Media are also possibilities). The video stream is broken up into IP packets and dumped into the telco's core network, which is a massive IP network that handles all sorts of other traffic (data, voice, etc.) in addition to the video. The video streams are received by a local office, which is adapted to deliver the video streams to the end users. (i.e. subscriber media presentation appliances). The local office may add local content (such as TV stations, advertising, and video on demand) to the received video streams. The local office is also adapted to house and operate the IPTV middleware. The middleware software stack handles user authentication, billing, channel change requests, VoD requests, and “last mile” distribution/routing/switching of the content bearing data streams.
Channels in the lineup are multicast from the national headend to local offices over a high capacity data work. There is usually a bottleneck in delivering content from the local offices to the subscriber residence due to the usually low capacity local loop (e.g. local DSL loop). Although Cable systems may be able to do so (since their bandwidth for a neighborhood can be 4.5 Gbps), even the newest ADSL2+ technology tops out at around 25 Mbps (and this speed drops quickly as distance from the DSLAM [DSL Access Multiplier] grows).
Bandwidth on the local loop (also known as “last mile”) is growing, and in some metro areas is considerably higher than 25 Mbps, but for now, most local IPTV offices overcome the problem of limited bandwidth on the local loop by multicasting a selected channel to some or all of the set-top boxes which have selected the given channel. That is, when a user changes the channel on their set-top box, the box does not “tune” a channel like a cable system. (There is in fact no such thing as “tuning” anymore—the box is simply an IP receiver.) What happens instead is that the box switches channels by using the IP Group Membership Protocol (IGMP) to join a new multicast group. When the local office receives this request, it checks whether the user is authorized to view the new channel. Upon receiving authorization, the local office directs the routers to add that particular user to the channel's distribution list. In this way, only signals that are currently being watched are actually being sent from the local office to the DSLAM and on to the user.
The present problem with multicasting content to the user's IP based media presentation device (e.g. STB) is two fold: (1) Channel zapping time-delay, and (2) Individual ad placement restrictions. Channel zapping time is mainly concerned with broadcast channels, which are typically delivered on the network as IP multicast streams in IPTV networks, where each IP multicast represents a specific channel. The use of multicast across the network is very efficient, as the traffic is sent only once up to the network edge, and only duplicated on a per-customer service in the last access device (DSLAM, PON OLT, Access switch, etc.). Although, there are number of sources creating long channel zapping time-delays, most of the zapping time in a well-engineered network is caused by waiting in the Set Top Box (STB) for the next available I-frame in the MPEG-2 stream (i.e. the size of the MPEG-2 GOP (group of pictures) in seconds), or IDR picture on the H.264 stream. In H.264 for example, IDR pictures may be up to 5 seconds distant, meaning that when a user is requesting a new channel, even if the network reacts very fast to the IGMP request, if the STB starts to get the stream right after the current MPEG-2 GOP/H.264 video sequence start (the I-frame/IDR picture) it must wait up to 5 seconds until it can display the picture on the screen.
Targeted Ad (commercial) insertion is also a big challenge in IPTV networks. Current ad insertion methods rely on a centralized ad insertion server in the main distribution hubs of the networks. This implies that for multicast streams, the commercials are placed based on large geographic areas, without per-user granularity, or per region. If per-user ad insertion is needed, than the multicast traffic must become unicast traffic and would create bandwidth explosion on the network.
Thus, there is a need in the field of IPTV for improved methods, systems and devices for distributing content to user media presentation devices.